The present invention relates to manually operated pumps for dispensing liquids in spray form from containers and, more particularly, to leak-proof dispensing pumps having atomizing outlet check valve means.
Manually operated pumps for dispensing liquids in spray form from containers are well known in the art and are increasing in commercial significance, especially in the United States, due to recent concern over the use of fluorocarbon gases in aerosol dispensers. Considerable difficulty has been encountered, however, in providing a low cost, high compression, manually operated dispensing pump which could be used in those applications which were heretofore satisfied almost exclusively by the aerosol dispensers.
In order to provide a manually operated dispensing pump having sufficient compression to spray the relatively more viscous liquids, and especially to provide the compression needed to dispense such liquids in atomized form, it is essential that the pump be constructed in a fashion which will cause substantially all of the liquid within the compression zone, i.e., the region defined between the inlet and outlet check valves, to be discharged when the pump is actuated. One example of a dispensing pump embodying this concept is disclosed in U.S. Pat. No. 3,913,841.
Another feature desirable in a manually operated dispensing pump is an outlet check valve which is operable to permit liquid to flow from the compression zone to the dispensing orifice only when the pressure of the liquid within the compression zone exceeds a predetermined release pressure of the check valve means, in a fashion analogous to the function of a pressure-relief valve. Such a valve ensures that the spray exiting through the dispensing orifice will have the necessary minimum velocity to prevent undesirable dribbling when the pump is only partially actuated. Such a valve has the further advantage of being self-sealing, i.e., it will prevent leakage from the dispensing orifice when the container is squeezed or inverted. An example of such valve means is embodied in U.S. Pat. No. 3,923,250.
Generally, manually operated dispensing pumps have proven to be relatively expensive by requiring a large number of parts, each individually complex and relatively costly to manufacture and assemble. Those pumps which have achieved the goal of a minimum number of parts, each individually simple and relatively inexpensive to manufacture and assemble, have done so by sacrificing desirable pressure potential. An example of such a pump is described in U.S. Pat. No. 3,749,290. Such pumps have limited utility for the more viscous liquids.
Accordingly, it would be desirable to provide a manually operated dispensing pump having the aforementioned desirable properties. Specifically, it would be desirable to have a leak-proof, low cost, high compression pump adapted to be secured to a container for dispensing a liquid product therefrom.